Elastomer die swellable into engagement with a cylinder by solvent contained in the ink



Aug. 3, 1965 J. MIKURAK 3,198,116

ELASTOMER DIE SWELLABLE INTO ENGAGEMENT WITH A CYLINDER BY SOLVENT CONTAINED IN THE INK Filed Nov. 2, 1962 2 Sheets-Sheet 1 IN VENTO ATTORNEYS Aug. 3, 1965 J. MIKURAK ELASTOMER DIE SWELLABLE INTO ENGAGEMENT WITH A Filed Nov. 2 196 ZCYLINDER BY SOLVENT CONTAINED IN THE INK 2 Sheets-Sheet 2 ATTORNEYS United States Patent D ELASTQMER DIE SWELLAELE INTO ENGAGE- MENT WETH A. CYLINDER BY SGLVENT (IGN- TAINED IN THE INK John Milrurak, Darby, I a, assignor to Arcos Corpnration, Philadelphia, Pa., a corporation of Pennsylvania Filed Nov. 2, 1962, Ser. No. 23$,tl08 6 Claims. (til. 101-677) The present invention relates to mechanism for printing and particularly mechanism for printing on the surface of round objects especially wires and more particularly electrodes which may or may not be coated.

A purpose of the invention is to use a swellable elastomer for the printing die and to hold the printing die in a groove in a printing roll or drum by the swelling action of a solvent used in the printing ink, so that the printing die is held in place without undercutting of the groove.

A further purpose is to drive a printing roll at a speed faster than the speed of progression of work arriving at a position tangential to the printing roll and there to rotate the work and imprint the surface of the work around the circumference.

A further purpose is to provide a tire which permissibly protrudes slightly beyond the radial diameter of the printing characters on the main printing die so as to drive the work for rotation.

A further purpose is to use an engraved transfer roll basically of metal to meter ink to the printing roll or drum, and to bring the engraved roll into very light engagement with elastomeric printing characters on the rinting roll, so that a page such as a sheet of thin typewriter paper interposed between the same for test purposes can be just freely pulled out without tearing.

A further purpose is to use an ink roll of fluorinated elast-omer so as to avoid deterioration in contact with the solvent.

Further purposes appear in the specification and in the claims.

In the drawings I have chosen to illustrate one only of the'numerous embodiments in which the invention may appear, selecting the form shown from the standpoints of convenience in illustration, satisfactory operation, and clear demonstration of the principles involved.

FIGURE 1 is a diagrammatical vertical section of the printing mechanism of the invention.

FIGURE 2 is an enlarged fragmentary axial section of the printing roll or drum of FIGURE 1, the section being taken on the line 2-2 of FIGURE 1 and omitting the conveyor.

FIGURE 3 is a diagrammatical axial section of the transfer roll shown in FIGURE 1, the section being taken on the line 33 of FIGURE 1 and omitting the associated operating mechanism.

FIGURE 4 is an enlarged fragmentary axial section of the transfer roll of FIGURE 3.

Describing in illustration but not in limitation and referring to the drawing:

In the printing of arc welding electrodes, considerable difficulty has been encountered.

At one time rubber dies were used which were cemented in place by glue. A set of dies under these conditions lasted about two shifts.

A mechanism was then tried in which elastomer printing dies received ink brushed on. In this case the dies lasted only about three hours.

Copper backed rubber dies were used but these were expensive and unsatisfactory.

Rubber dies were also used which contained a gripper ring and were assembled by disassembling the printing roll or drum. This proved to be cumbersome and expensive and unsatisfactory.

Rubber dies were also mounted in dovetail undercut slots by the elasticity of the rubber. This proved to be complicated and expensive also.

Efforts have been made in the present invention to overcome these difficulties. By the present invention several changes have been made in the printing technique which have greatly improved the results so that dies are now lasting of the order of 152 hours (2 million impressions) and cost 44% as much as the rubber dies cemented with glue which ran 28 hours, representing a cost of only 8% as great as formerly. The new dies also are easily replaced when required.

In accordance with the present invention the elastomer dies extend into a groove around the circumference of the printing roll or drum. The groove is free from undercut and is preferably parallel sided. Therefore the die is not likely to be torn in insertion or removal. The rubber used for the dies is an expanding rubber in contact with the ink solvent, preferably butyl rubber. Another solvent expanding rubber can be used, such as natural rubber, GRS, or the like.

The solvent which accompanies the ink is a solvent which tends to make the rubber expand. It may be any one of the hydrocarbon or chlorinated hydrocarbon solvents such as benzol, toluol, xylol, methylene chloride, carbon disulphide, chloroform, ethylene dichloride, kerosene, naphtha, tetrachlorethane, trichloride ethylene, turpentine, Stoddard solvent, or any one of the various other rubber-swelling solvents may be used.

In accordance with the invention the printing roll or drum is driven at a speed faster than that at which the electrode or other work is carried and desirably has a tire slightly protruding beyond the elastomer printing die so that the work is rotated and the printing is applied around the circumference.

It has been found that superior results can be obtained by using an engraved transfer roll which has recesses of a size to hold the quantity of ink desired. The pressure between the elastomer die and the rigid suitably metallic transfer roll is critical. I find that they should be adjusted so that a piece of thin paper such as thin typewriter paper having a thickness of about 0.003 inch can be just pulled out between the printing die and the transfer roll without rotating them and without tearing the paper.

I find that it is very desirable to use a special rubber or elastomer for the ink roll which will not deteriorate in contact with the solvent and will give prolonged service,

The work of course comprises suitable wire-like or:

rod-like electrodes 20, which desirably have a metallic wire 21 and a coating 22 containing an are or gas welding flux, suitably consisting of one or more metallic powders and oxides and silicates, bounded on the wire 21 and baked. The invention is applicable however to printing on wires alone.

The purpose of printing on welding electrodes and the like is to avoid confusion between different welding compositions, which might require rejection of welded components.

The electrodes are carried by an inclined apron 23 and picked up by a conveyer 24 suitably a plurality of chains side by side driven in suitable manner by a set of cooperating sprockets only one of which is shown. The sprocket 25 is on a shaft 27 driven by a belt 28 which engages the shaft or a pulley thereon so that the conveyor advances at a forward speed suitable to bring one electrode 20 at a time into tangential engagement at 30 with a suitably metallic printing drum, or roll 31 which has printing dies 32 maintained on its circumference as later explained.

The printing roll or drum 31 is turned at a linear 7 forward speed as shown by the arrows which is greater than the forward speed of the electrode engaged in suit able notches 34 on the eonveyer, sufficient to rotatethe The cont'act between the ink transfer roll 37 and the printing roll'or drum Slis critical. For good results the printing roll or drum should have its axis position adjusted until it is possible toinsert a thin piece of paper such as a thin sheet of'typewriter paper of thickness of about 0.003 inch between the, turning ink transfer roll 37 and the printing drum'or roll 31 and then pull the sheet out electrode through substantially a complete circumference" While it is engaged with the circumference of the printing 7 roll or drum so that the printing will extend desirably around the electrode without overlapping. Suitable drive means such as an electric motor coupled by belts and pulleys to the drum 31 may be'used to turn the drum 31 at the desired speed indicated above. The printing drum or roll is provided at the axis with stub shafts 35 which are suitably made of plain carbon and'theywill not be described in detail with regard to.

the other rolls.

present invention. r

Displaced suitably above and coaxial with respect'to the printing dies on the printing roll isa suitably metallic ink transfer roll 37 which has a series of-opposite spiral These bearings form no part of the These shafts and bearings combined without turning the rolls or tearingthe paper and with slight feeling of resistance to the fingers. This means that 'the printing roll or drum 31 should have dies which are just touching the inktransfer roll 37 andno more. Under these conditions it will transfer ink but will not 1 produce a blur 'or smudge' The printing roll 31 has a plurality of circumferential grooves 56 which extend fully around the circular circumference and desirably have straight sides 5'7 as shown, inany case without undercut.

. The main printing die 33 is made of elastomer, suitably a rubber which will swell under the solvent used in the ink; The die is preferably made of butyl rubber but itmay be made of natural rubber or of GRS. The

die when the solvent isabsent just freely fits in the groove but once it comes in contact with the solvent it grooves 38-whose size is chosen to be adequate to hold;

the ink content to be metered. I find that grooves in'these rolls preferably are of theorder of 0.002 inch deep, with a distance between humps 40 of about 0.0085 inch, and

preferably a contour as 'shown in, FIGURE14;

The ink transfer roll also engages an ink roll 41 which" has an axis parallel to theother two rolls and is mounted on a bearing'combination as'above described.

The ink roll at its lower portion is immersed in ,an

ink supply 4,2 mounted in an ink reservoir'43. Thefink swells and veryfirrnlyengages in the groove. The die portion 58 in thegrooves'supports a body portion 60 whichextends in both directions parallel to theaxis beyond the groove 56 and has on the surface at 61 suit- I ably slightly raised type, which print letters and numbers 62 as required;

The printing die extends endlessly. and meets suitably in an abrupt end to end'ellgagement, the ends of the printing dies being staggered around the. circumference.

V The durometer for the printing die is desirably about 30.

At one or both ends of the printing drum or roll there are suitable not undercut preferablylstraight sided circumferential grooves 63 which receive an eiastomer tire 64 which is desirably of slightly larger radius than the printing die at the point where the type is located, suitis desirably constantly replenished and'maintained in the reservoir by a circulating pump of well knowncharacter. An ink container 44 has a supply of liquid ink 45.

Mounted above the container is an electric motor 46 which drives a shaft'47 which operates .a rotor in a pump 48 of well'known character, the pump lifting ink through an inlet pipe 50 controlled by a normally open valve 5110 enter the top of the ink reservoir 43.: 'Ink constantly flows out pipe 52 to discharge back in the ink container 44-. r

v The ink roll 41 and also the transfer roll- 37 which engages it and the printing drum or roll 31 which'carries the dies which engage the transfer rollare driven by electric motor 53 driving pulley 54 which drives belt 55 which drives pulley 56 on the 'shaftfof the ink roll 41.

The rubber ink roll is constantly exposed to solvent ably extending0.00 05 to 0,004 inch beyond the letters on the die. This makes the tire grip and rotate the work to print around the circumference.

The tire isalso a butyl rubber or other swelling rubber and is held in place in the same way;

in which the ink is dissolved and the rubber is in dangerj f of deterioration. It is 'therefore preferable to use a rubber or an elastomer which is very re'sistantto solvent such as fluorinated' elastomer of the character of Viton Du Pont).

This material is acopolymer of vinylidene fluoride and; a minor amount of hexafiuoropropylene which has: a tensile strength in excess of 2000' p.s.i.,-a temperature range of 40 to 600 F., good abrasion-resistance, to oils,

remove.

In some casesas'in the case of the tire 65 there may be type on the tire; i w l The tire preferably hasa slightly higher durometer.

than the printingdie so thatwhen the printing die is of durometer 30 the tire is desirably ofdurometer about 40. In operation of the device the tires and dies are .readily removed by removing the printing drum or roll from the ink'in which case they shrink and will readily To insert them, they are simply placed in position and exposed "to solventand swell immediately to grip. The swelling is longitudinal as well aslateral so that the seam at the endfof the die isnot noticeable.

With the printing die in placeand the die properly adjusted in relation to the ink roll, the speed of driving the combination ofr-printing rolls is adjusted with respect 1 to the speed of the' conveyeruntil the work is completely chemicals .and solvents, good mechanical properties, good' resistanceto compression set, good resistance to sunlight i and outstanding resistance to oxygen and ozone.

The inkroll' 41 should havej'a durometer of between 55 and 65. r I

" The ink roll41iis'constantly applying 'ink to the ink transfer roll 37 and wiping it off f-rom-theink transfer roll so that a ghost film of ink is left onthe inktransfer roll totransfer'to the printing die.

printed without overlap. his then merely necessary to supply electrodes to be picked up in the notchesin the 'conve'yer and be. printed bythe printing drum or roll.

7 In operation, applicant" has obtained satisfactory results using an ink roll of Viton, a methylene chloride as a solvent, and an iron oxide base printinginln' 7 The' ink may beof any well known character when is capable of dissolving inany one of the swelling solvents sand no specialjtype of inkis required A-suitable ink "The suitably metallic ink transfer roll, 37 is-desira l I maintained in firm engagement with the ink roll- 41 but the engagement should be insufficient to deform the ink roll. a o 1' is" one of the ,WfillfkIlOWl'l iron-oxide base printing inks.

' In view of my invention and disclosure variations and 'rnodifications to meet individual whirn or particular need will doubtless, become evident to others skilled in.the

I I art, to obtain all or par-tof the-benefits of my'invention without. copying structure sho'wn, and Ither'efore, claim all such insofar as they fall within the reasonable spirit and scope of my claim.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In marking equipment, a marking drum having an annular groove which is free from undercut, an elastomer printing die extending around the circumference of the drum fitting into and occupying the groove and having printing characters on the outside, said elastomer being swelled upon contact with a solvent and shrinking upon being removed from contact with said solvent, a body of ink including a swelling solvent for said elastomer die, and means for transferring the ink including the solvent to the die, whereby the die is held in the groove due to the swelling caused by said solvent.

2. Equipment of claim 1, in which the side Walls of said groove are parallel.

3. Equipment of claim 1, in which said die extends in a direction parallel to the axis beyond the groove on the face of said drum,

4. Equipment of claim 1, in which said die is composed of butyl rubber.

5. Equipment of claim 1 which has a further groove around the circumference of said roll at a difierent axial position, said further groove being free from undercut, and an elastomer tire fitting in said further groove, extending out radially beyond the die and held in said further groove by the swelling action of said solvent.

6. Equipment of claim 5, in which the side Walls of said further groove are parallel.

References Cited by the Examiner UNITED STATES PATENTS 394,987 12/88 Mclndoe 131-24 X 430,269 6/90 Clause et a1 101-348 X 746,376 12/03 Prescott 101-40 1,240,078 9/17 Morgan 101-348 1,549,595 8/25 Merrill 101-40 2,278,982 4/42 Frolich 101-348 X 2,578,921 12/51 Cramer 101-350 2,653,540 9/53 Johnson 101-348 X 2,696,781 12/54 Hunt 101-40 2,856,058 10/58 Todd et al 101-38 X 2,871,783 2/59 Schrnutz 101-377 2,925,624 2/60 Stahl et al 264-135 X 2,943,567 7/60 Pannier 101-377 2,950,671 8/60 Allen et al 101-40 3,086,461 4/63 Gill 101-377 OTHER REFERENCES Synthetic Rubber (Whitby), published by John Wiley and Sons, Inc. (New York), 1954. (Eages 874 and 875 relied 011.)

Printing Inks (Ellis), published by Reinhold Pub- 25 lishing Corporation (New York), 1940. (Page 240 relied ROBERT E. PULFREY, Primary Examiner.

EUGENE R. CAFOZIO, Examiner. 

1. IN MARKING EQUIPMENT, A MARKING DRUM HAVING AN ANNULAR GROOVE WHICH IS FREE FROM UNDERCUT, AN ELASTOMER PRINTING DIE EXTENDING AROUND THE CIRCUMFERENCE OF THE DRUM FITTING INTO AND OCCUPYING THE GROOVE AND HAVING PRINTING CHARACTERS ON THE OUTSIDE, SAID ELASTOMER BEING SWELLED UPON CONTACT WITH A SOLVENT AND SHRINKING UPON BEING REMOVED FROM CONTACT WITH SAID SOLVENT, A BODY OF INK INCLUDING A SWELLING SOLVENT FOR SAID ELASTOMER DIE, AND MEANS FOR TRANSFERRING THE INK INCLUDING THE SOLVENT TO THE DIE, WHEREBY THE DIE IS HELD IN THE GROOVE DUE TO THE SWELLING CAUSED BY SAID SOLVENT. 